This workbook outlines methods of comparing Current Period to Date vs the Previous Period to Date based on 3 Parameters: Date Selection (Calendar Param), Period (List Param, i.e. Year, Quarter, Month) and N Periods Back (1 -100).
Some of the techniques used in this workbook have been improved upon since its initial creation. I will be updating soon (2016-04-12 RZ)
For more, check out my Think Data Thursday on Dates in Tableau
Supplemental Workbooks can be found in my comments in the link above.
9.0, however no LOD functions are used.